1. Field of the Invention
The present invention relates to a rigid-flexible circuit board, and in particular to a rigid-flexible circuit board including an impedance control structure.
2. The Related Arts
The vigorous progress of electronic industry makes printed circuit boards playing an important role in taking the place of the conventional ways of arranging flat cables. Further, the development of a flexible printed circuit (FPC) brings a significant upgrade of the electronic industry. The FPC is a technique that a flexible copper foil based substrate is subjected to processing to have wiring directly laid on the substrate. The industry is now continuously devoting themselves to researches and developments of circuit capacity that can be adopted for miniaturization, weight reduction, and dense integration of electronic components of electronic and electrical appliances by increasing the layers of a printed circuit board to form a multilayer printed circuit board for greatly expanding the area for wire laying. Various devices, such as mobile phones, notebook computers, and satellite navigation systems, have already adopted the technology of multilayer circuit board.
The printed circuit boards and the flexible printed circuit boards each have their own advantages and characteristics and different types of circuit boards are generally used in different applications. Due to the increasingly emergence of new and diversified electronic products in the market, the conventionally used simple printed circuit boards or flexible printed circuit boards are generally incapable to satisfy the emerging needs. Thus, a compound circuit board or a rigid-flexible circuit board is available for such needs.